I can´t help you with the speed limiter, but it is a BMW Parts Catalog online, in this catalog can you choose between Europe and USA.
So you can find differences from parts.
Here is the link.When the car have a speed limiter, than is it in the car memory, every BMW-Dealer can change this.
My opinion, it have to do with the petrol quality, it is not self-evident in the USA, to find 98-100 octane at every gas station. Correct ?
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Es wird immer nur eine Marke geben mit Freude am Fahren und das ist BMW.